1. Field
The present invention relates to an optical film, a polarizing plate and a liquid crystal display device.
2. Description of Related Art
The liquid crystal device is a space-saving image display device with low electric power consumption, and the use thereof is increasing every year. A wide viewing angle liquid crystal mode such as a VA mode and an IPS mode is being put into practice, and accordingly, the demand for a liquid crystal display device is rapidly spreading even in the market where a high-quality image such as a television is required.
As the use of the liquid crystal display device is expanding, the liquid crystal display device has a large size and has been required to have a high-quality texture. Meanwhile, when having a large size, the liquid crystal display device becomes heavy. For weight reduction, thin film thickness of various members proceeds.
The liquid crystal display device is composed of a liquid crystal cell and polarizing plates provided on a viewing side (front side) and a backlight side (rear side) of a liquid crystal cell. Both the polarizing plates are bonded to substrates on both sides of the liquid crystal cell by means of an adhesive bond and the like. The polarizing plate used in the liquid crystal display device generally configured to include a polarizer which is composed of a polyvinyl alcohol (PVA) film and the like, on which iodine or a dye is adsorbed and aligned, and transparent protective films which are adhered to inner and outer sides thereof, but since the PVA is hydrophilic, the polarizer is sensitive to a change in temperature or humidity, and thus easily elongates due to a change in ambient environment. Due to the elongation of the polarizer, the polarizing plate (the laminated body of the optical film including the polarizer) elongates, and as a result, warpage occurs on a liquid crystal cell to which the polarizing plate is bonded, and a display unevenness (light leakage occurring on four corners of the liquid crystal cell) occurs on the liquid crystal display device. As various members have been recently thinned, light leakage due to warpage of the liquid crystal cell has become a trend.